1. Field of the Invention
This invention relates to a range finding device particularly useful in golfing to measure the distance to the green which the golfer is approaching.
2. Description of the Prior Art
After teeing off on a typical four or five-par hole, the golfer is often left with a second shot of up to 200 yards or more. In selecting the club for the next shot, it is important for the golfer to accurately determine the distance to the pin on the green, so that he may reach the green without overshooting, or undershooting.
There have been several methods of ascertaining the distance to the pin. By far the most common method is simply to estimate the distance based upon prior knowledge of the particular golf course or based upon certain landmarks adjacent to the fairway. Such estimates are typically very inaccurate.
Another approach in determining the yardage to the green for the golfer's next shot is for the golfer to pace off the distance one step at a time, and then estimate that each step is a yard. This procedure is extremely time consuming, and thus detracts from the enjoyment of the game by the following group of golfers.
A few hand-held devices have been developed for the golfer to use in distance determination. For example, one particular type of range finder is a slide viewing window having a vertical extent calibrated in yards while the space between the upper and lower viewing lines is adjusted. The golfer sights through an opening in the range finder and adjusts the upper and lower viewing lines until they correspond substantially to the upper and lower extent of the pin located on the green. Once this is done, the viewer looks to the side of the indicator to read the range in yards, thereby allowing him to select the appropriate club for his next shot. While this is a comparatively simple device, it still requires a relatively steady hand of the golfer to hold the sight window in place while aligning the upper and lower movable lines.
Another range finding device is disclosed in U.S. Pat. No. 3,868,692, one of the coinventors thereof being a coinventor of the present invention. That device comprises a portable unit adapted to receive a RF signal emitted by a transmitter on the pin and to estimate the distance to the pin based on the intensity of the signal. While this device is superior to other prior art devices, it still lacks sufficient accuracy.
None of these prior art devices take into account the effects of the wind in the determination of the distance to the pin. Any head wind or tail wind can effectively increase or decrease the distance for the purposes of club selection. Furthermore, a cross wind may require shot placement to the left or right of the pin. In addition, all of the prior art range finding devices require the golfer to estimate the proper club selection based upon the indicated yardage.